During oil and gas underwater field development, more and more catenary risers are used. The dynamic behavior of the touchdown point of these catenary risers can be complicated. Software tools can be used to simulate and analyze the dynamic motions and stresses at the touchdown point, but different software tools may use different analysis approaches, and produce different results that may be contradictory or inconclusive. Apparatus and methods have been proposed for testing the dynamic motions and stresses at the touchdown point of catenary risers.